But somehow marketing in all these different languages isn't overwhelming enough to stop them from selling their goods in these countries.
Eh, yes, it is actually. Many online services aren't universally available throughout the EU because they aren't translated into the local languages, and it wasn't so long ago that we were reading here on Slashdot about how the EU Commission is annoyed by geo-blocking of services. These rules aren't just about Amazon and Google you know. They also apply to a huge long tail of smaller companies who given a choice between "having to respond to letters from the Bulgarian government, written in Bulgarian" and "spending the time on other things" will choose the latter.
And if you're worried about efficiency, let's remember that it would be FAR more efficient to only tax corporations, than to tax EVERY SINGLE CITIZEN.
No, it really wouldn't. This whole fiasco is demonstrating that very clearly.
Taxing people makes sense. People cannot be in multiple countries at once: figuring out if someone should be a taxpayer can be as simple as adding up how many days they spent in the country. People are what use government services. Companies don't use them anywhere near as much - companies don't get sick and go to hospital, they don't drive down roads, they don't draw pensions etc. Companies get the services of the legal system, although sometimes those "services" may involve being sued by a competitor and other times they have to pay fees to use the courts anyway.
What's more, the moral justification for taxation fails when applied to companies - they suffer taxation without representation. Companies cannot vote. Heck, they get demonised even for talking to governments, so voting is entirely out of the question.
The biggest problem with taxing companies though, is figuring out how to slice the pie between different governments. Unlike people, companies can be in many places at once. So suddenly every cash-starved government feels like they're entitled to a bigger piece of pie. It turns into a crazy tug of war with the company being torn apart in the middle.
In the old days this problem didn't matter much because large scale free trade is a relatively recent thing, so previous generations of companies were mostly based in one or two places. But sometimes, especially with modern companies, there's no really good way to divide the spoils up. Where does Google make its profit? Is it in California where the search engine is developed? Is it in Ireland where the advertising contracts were signed? Is it in Germany where the datacenter handled the request, or Oregon where the data the datacenter served was generated? Is it where the customer who clicked the ad is located, or the customer who paid for it? If it's the latter, what if the customer is itself a transnational company?
These questions are enough to feed an army of lawyers and accountants for all eternity, and the end result will still seem unfair to big groups of people. Accusations of "avoidance" (whatever that means) will still fly. There is just NO WAY to do this well.
The logical conclusion to all these problems is to simply zero out corporation taxes entirely, and raise revenue from the individuals who live there. Of course this is deeply unpopular because corporation taxes feel "free" .... it's harder to understand the impact they have, whereas it's easy to understand the impact that less money in your wallet has. So I think we will continue to see a never-ending stream of asshattery and countries finger-pointing at each other over tax, especially tax of perceived foreign companies, because taxing them looks to politicians suspiciously like free money.